David Blunkett's decision to sell his controversial DNA Bioscience shares may take some of the heat from the Opposition claims of an apparent conflict of interest, but it is unlikely to end them entirely.

The prime minister is currently standing by Mr Blunkett

Put simply, by selling the shares Mr Blunkett has not corrected the error - if there was one - of buying them in the first place then keeping them after being brought back into the Cabinet.

For one thing, the ministerial code insists there should be no "apparent" conflict of interest, which Mr Blunkett's statement clearly suggests he accepts there was.

Then there is the question over his judgement in taking a directorship and buying shares during his brief period in exile if he already believed he had a guarantee of a Cabinet job after the election.

He has already admitted that, in hindsight, he should probably have acted differently over the whole matter.

And it is on his judgement that opposition politicians are now concentrating and, worse for the prime minister, that is bound to feed into the rumblings over his own judgement and claims his authority is waning.

One of the most telling factors was the fact that so few senior ministers appeared ready to ride to Mr Blunkett's cause.

Recent biography

Most observers expected the usual panel of senior ministers to be wheeled out at the weekend to defend the work and pensions secretary after the stories about his relationship with the private firm.

That did not happen. Mr Blunkett received robust support from the prime minister but only Cabinet Office Minister John Hutton joined in.

There may have been little enthusiasm for that amongst those of Mr Blunkett's colleagues who he so publicly lambasted in his recent biography.

But ministers' reluctance was seen as another example of Mr Blair's alleged lack of grip on his Cabinet and the fact that they were looking beyond his premiership.

The prime minister certainly needs to keep a strong ally like Mr Blunkett in the Cabinet, not just because they are on the same reforming agenda at a time when other ministers are expressing serious doubts, but because Mr Blunkett offers a man-of-the-people sheen to Mr Blair's image.

Mr Blunkett has admitted he should have done differently

And, despite reports of a recent spat between them over the depth of welfare reform, the two remain both personally and politically close.

The other calculation ministers are undoubtedly making now is even if Mr Blunkett has managed to kill off this latest row, will the drip, drip, drip of claims continue to weaken him.

If the knives are out for him in some sections of the media, as claimed, that must partly be because of the defiant way the prime minister brought him back into the cabinet after his resignation in the wake of the affair around his nanny's fast-tracked visa.

Many at the time believed his rehabilitation was far too speedy and that the prime minister was ill-advised virtually to guarantee him a job in his new, post-election Cabinet after only weeks in the cold.

As ever, Mr Blair will stand by his man as long as the continuing controversies do not impact on the way he is doing his job of delivering the prime minister's cherished public sector reforms.

But if he becomes distracted from completing that mission, or the rows start to seriously damage the prime minister, things may change very quickly indeed.